Reverse Lock Issue

[79Merc175]

Hi Folks, I've got a 1979 v175 and when I back the boat up in the water the motor rears up towards the boat then slams down once I let off of the throttle. The tilt/trim system works just fine and is one of the old prestolite systems which has the AC motor that sits on top of the rectangular resevoir. Also, I've made sure that the bypass (knurled knob) is locked. The only thing thats different about this sytem that I can't find much information on is that there is what appears to be a solenoid or valve which comes out of the bottom side of the trim pump resevoir which has a wire attached to the end of it. I've been told that this is a reverse lock that holds the motor when in reverse but again I can't find any info, part numbers, etc on this mystery piece of the puzzle.

I appreicate any help that can be offered for this.

 

[Laddies]

Re: Reverse Lock Issue

The pink wire goes to a revese interlock switch in the control box a supplies 12V to the solinoid to lock the engine down in revese, the rest of the time the engine is released so apparently you have no power to it in revese.

 

[79Merc175]

Re: Reverse Lock Issue

Thanks Laddies. I'm still trying to understand all of this so forgive me but I assume from your post that the pink wire you're referring to is the one I mentioned that I see attached to the valve/solenoid coming off the side of the resevoir. Does the motor have to be cranked and running to test whether or not 12v is going to it or can I simply have the key switch turned on and put the throttle in reverse and expect the voltage to be present. In addition, if 12v is present then I assume that the only other failure can be with the valve/solenoid itself; any idea what part # this would be or if one of these can even be found any longer?

 

[Laddies]

Re: Reverse Lock Issue

The engine don't need to be running but the key must be on for the lock to work. Here's a link with a parts break down. http://www.mercruiserparts.com/Show...ump(S/N-Merc-5393736/Mariner-5316380+&+Below)
If a wiring diagram we help I can post one.

 

[79Merc175]

Re: Reverse Lock Issue

Hi Laddies. Thanks once again for the reply and the link to the parts breakdown. If its not too much trouble I would like to have the wiring diag as well for future reference on this aging merc.

 

[Laddies]

Re: Reverse Lock Issue